HI folks,
Eldest son has just bought a 2000 Mk 2 punto sx with 8v engine. Its got about 80k miles with an uncertain service history. I got some buying advice here a few days ago as it is a long time since we have had a petrol car (Multipla and Rover 75 diesels currently). While the car ran fine on a test drive before it was bought, when it gets warm, it tends to lose power and stutter and then clear itself while running at normal engine speeds. It seems to be more likely to start when accelerating from about 40mph in 4th or 5th, dropping a gear makes little difference. It then seems to clear itself and works normally. No sign of an engine management light though! Where would I start?

Perhaps unrelated, I notice that there is a female electrical connector on the top of the cam cover close to the oil filler with no male connector plugged in. Is this just a cam sensor for a rev counter that this model does not have? There is a cable running alongside going down towards a crankshaft sensor possibly?

Does the red engine management lamp come on briefly during the check on initial start-up? It has been known for people to disable the lamp to cover up a fault when selling.

Models after 2001 had a cam sensor on the cam cover to meet Euro 3 emission standards by running sequential injection. Your 2000 model doesn't have one and fires all 4 injectors in a batch. You should have a small wire in a corrugated sleeve that runs down to the oil pressure switch, and beside that should be the crank/rpm sensor cable which runs upto the top of the camcover where it plugs into the engine loom. Are you saying there's a third connector?

Intermittant loss of power under load suggests a misfire- check the plugs and leads and replace if necessary.

Thanks for reply D4nny8oy

The engine management light does seem to work correctly - coming on for a few seconds during the light check phase. The crank sensor and oil pressure wiring seems in order as you say. Its just there is another connecting socket on top of the cam cover near the timing belt cover which is not connected to the wiring loom.

Also I have just noticed the lower lamda sensor cable is not connected to anything. The connector is fixed to a bracket near the cat facing upwards as I look down but no connecting wire and what's even stranger, no plug hanging out of the loom to connect to it! Now I am looking at all this in the dark - maybe it will look different in daylight though I doubt it! Is it possible that the 2000 model had a second lamda that had no connection to the ECU?? What is the function of the second lamda?

I will try the plugs and cables (although there is no evidence of leakage on the HT leads on this dark night) but the problem seems to get worse when the engine is warm and is intermittent - not so sure this would be plugs etc Incidentally the engine idles perfectly and when it is running ok it is quite sweet with plenty of power. Regards

Lamba possibly at fault?
If its Disconnected IIRC that it runs fine when cold - but like "Sugar" when hot?

Also 2000 dont use phase sensor on rocker cover - if you have a phase sensor then possibly had an engine swap?

Ziggy

Does the year 2000 8V engine have 2 lambda sensors? As I said I seem to have an after-cat sensor with no visible plug on the wiring loom for it. Perhaps it is tied up somewhere at the back of the engine when somebody thought it was a good idea to run without the second Lambda connected. I will have another look in the morning.
If there was an engine swap to a later unit, could there be any other mismatch that is causing my intermittent high speed power loss / poor running.

I would of thought there should be 2 wired up, have on mine. Before the cat, and after the cat. If its just above the cat on the right side, the wire kinda runs down and connect up to another wire. Once you run it all the way down there should be another wire running down after the cata which should be the second one.

yeah im crap at explaining would upload pics if i wasnt at work.
Maybe you should upload some pics to show us what you mean

Thanks all for the help so far. I have attached three photos - one general one of the engine, one of the unconnected connector for the lower lambda sensor and one of the unconnected cam sensor. If the engine was changed, it looks pretty professional otherwise with no giveaway messy wiring etc. There is a breakers yard 'punto 05' mark on the alternator which I was assuming was only the alternator.

We drove it from cold this morning and it is really driving quite well except when it gets fully warm (10 mins driving from cold), if you let speed and revs down, such as after turning at a junction, it starts misbehaving by losing power and running unevenly and then picking up again. All of course without the EML showing.

Big son now heading off to buy the ubiquitous Haynes manual before delving much further. Oh for my old Citroen ZX turbodiesel that had 1 single wire going to the engine (to stop it) which went to 250k miles before I sold it!!!

Picture two - just looks as though somebody has replaced the cam cover at some point and not removed that housing from it. (My cam cover has a moulding for a sensor to be clipped onto it, but seeing as it's the same age as yours, it hasn't got one lol)

On the plus side, you don't appear to have the infamous cam/rocker cover leak lol

OK more revelations,
After an investigation that would put CSI in the shade (!!!!), we reckon there is an 05 engine fitted to our 00 punto Mk 2 8 valve. Please see the attached photo for the evidence! Given that the same yellow paint is used on the alternator and the block, we are pretty sure that it was re-engined as was suggested by ZIGGY.

It looks like the original inlet manifold or at least the management system was retained as we have both ignition keys and the same key opens both door locks and starts the car indicating its original. Is there anything to confirm this in the pictures?

Now are these two compatible i.e. we have a wiring harness with just one lambda connection (connected to inlet manifold side of Cat) and an exhaust system with two! Will the single Lambda be OK - is it the same spec as a twin lambda setup? Also we have the cam sensor but no where for it to feed to - this may not be a problem.

Interestingly the just-purchased Haynes manual for the mk 2 (99 to 03) only mentions the two-lambda setup. Also Haynes includes all the wiring diagrams except the engine management!! The car passed its NCT (similar to MOT) in Jan from its history, when I would say this engine was fitted and managed to get passed the emissions test so I am assuming it did run OK at idle at least at that time. Again our problem is uneven running and power loss when accelerating from a low speed - though only when warm.
Son gone to University now - we will see how it reacts and try code reading (although no EML showing) next weekend.

Unfortunately we have seen the dreaded steering warning light today also which of course never turned up on the test drive. The steering appears to be working fine - I will search the forum for info on this!

Thanks again for all the help. Dermot

Think it is a different engine. I have an 03, before the new version, MK2b i think they are, came out. In the first picture where you are pointing, that is where the top lambda (just above you in the same pic) connects to in my car. And i only have 2 of the sensors, 1st pre cata, like yours in the pic only wired into a different place. and the 2nd pre cata.

I think the engine was prob from a 05 punto model, which i think is a mk2B, which would be slightly different from your 00.

And in the second pic, that might of been wired up to the 05 model.

But dont take my word for it, i haven't seen a 05 to be sure of it.

But if this is the case, maybe this is the cause to your power loss and everything.




Also as for the power steering light coming on. Sometimes on puntos it just flashes up. Unless its on all the time, and your steering is iffy (and you will know when it is). Should be fine.

Well those pics solve it. Euro2 engines (pre 2001) like what yours should be, had no cam sensor and only a pre-cat lambda sensor. Euro 3 (post 2001) ran both a cam sensor and pre- and post-cat lambda's.

As you have suspected, someone's swapped the engine for an '05 unit. Because they've used the original engine management ECU (euro 2) and wiring, it isn't concerned about the cam and post-cat lambda as it never had them on the original engine- hence why no errors and why it passed the emissions ok- it still 'thinks' it's the earlier engine. The swap itself shouldn't be the cause of the faults, as long as the components are working ok, as the parts are the same across the two.

Thanks for that DAN.
My exhaust has two lambda fitted; one at the manifold and the other below the CAT (I presume the Cat is the wider bit!). Only the top one is connected up. Do I gather from you that there can be two lambdas pre cat and one post cat??? Certainly my wiring harness indicates there was only one fitted originally on our car.

What I really need to know is whether the Lambda units are different i.e. is the single pre cat one the same spec as the pre-cat one on a two Lamda one with Lambdas before and after the CAT.

Latest report from Son No 1 just now- performs fine on moterway but struggles in slower driving - spluttering and jerking with intermittent power loss? Maybe it is something differently entirely?

Regards

Dermot

Yep, early models only had 1 (pre cat). Later models had two (pre and post). The engine was clearly swapped with the manifold/cat still fitted, hence why you now have an extra sensor post-cat.

Both lambda's are the same which was always handy for diagnostic purposes- swap them over and see if the fault changes.

You mean there is also another (post cat) Lambda sensor? So you do have 1 pre cat, and 1 post cat? 2 in total? But the Post cat is the one that isnt connected?

D4nny8oy seems to know more about the engine then me. But if you are ment to have an Euro2 type engine, you should only have 1 in total lambda sensor, which would be pre cat.

In your first pic where you are pointing, wire above it is your pre cat. If you follow the wire that you are point at down, you come to another Lambda sensor?


I find it wired that there is a post cat sensor in place if your car is 2000 before the new Euro3 for the new 2 sensor set up. If its a 2000 surely there should of only been a pre cat sensor, not both in place? Unless they also put a new Cat in it aswell as engine...

Think im confusing myself now aswell

Sounds like your MAP sensor is playing up. In live data check the hpa readings

DAN 91: Yep the lower sensor is there below my hand in the pic but has nowhere to connect but now I am ok with that after D4NNY8OY's last post.

D4NNY8OY: Sorry I seem to have missed your post before my last reply - good to confirm it should run with one Lambda. I will try swapping around Lambdas next weekend but remember I have no EML showing.

Martin: Again did not even try fault code reading let alone live data (not long ago I had a citroen diesel with just one wire to the engine (oh Joy!!). My brother has a generic fault code reader that runs thru a laptop- not sure what it will do - I will see next w/e when the car is back. Any other way of checking the MAP - what happens if I disconnect it - could this confirm faulty unit. Again should I have an EML showing if this was at fault?

I missed D4NNY8OY post aswell. Hes most likely right about them keeping the 05 cat with the 05 engine hence why you have it. Got myself confused thinking you still have the original cat and someone had done their own makeshift hole for a post cat then not bothered connecting it up which would be werid.
So aslong as they have wired and fitted it correctly it should work fine.

With the question of loss of power. When was the car last serviced? Not sure if you have but check the spark plugs/leads and air filter. Recently had problems with my Punto nearly stalling at lower gears, seems i needed new spark plug leads.

Dermot said:

I will try swapping around Lambdas next weekend but remember I have no EML showing.

Click to expand...

That's ok. If it is a lambda related issue then the loss of power/misfire fault will hopefully no longer be apparent after fitting the other sensor. It's sitting there doing nothing anyway and saves buying one to try.

TBH, lambda faults tend to appear on part-throttle loads (under 75% throttle opening) when upto temp. Under full throttle, the lambda readings are ignored, so the fault won't be apparent. Whereas an ignition-related misfire (plugs/leads) tends to occur mainly under full load at low rpm (3rd/4th gear acceleration from 1500rpm). It's something to test and check before you swap them over.

Final update hopefully!
Well the big son struggled on with the car for a week after last post with the same symptoms. Last weekend we swapped Lambdas as usefully suggested by Forum members (given that we had a spare due to the engine swap). Unfortunately we got no improvement and we were inclined to rule out the Lambda at this stage. We replaced air filter and plug leads and waited another week with symptoms still evident.

At this stage we purchased an ELM 327 lead and downloaded Fiat ECUSCAN - our first venture into diagnostics!. This did show a possible Lambda fault occasionally although when it was cleared, it did not necessarily re-occur. However when we graphed the output from the lambda, we noticed a peak of 3.7v occurring occasionally, although it was giving more normal outputs (as far as us novices could determine!) most of the time.

At this point we got a brainwave (about time I hear you all chorus!)and 'borrowed' my octogenarian mother's lambda from her 2002 Stilo (yes the family is polluted with Fiats!) after checking it was the same spec as the Punto. Hey presto, all uneven running cured and a sensor output of less than 1 v on FiatEcuscan. As I write, the good Lambda is returned to its home in the Stilo and son number one is about to splash out on a new Lambda.

So a story that ends well, and this post is to thank all - no doubt help will be needed again in the future.